1. Field of the Invention
The invention relates to a sealant, and more particularly to a sealant composition for a one drop filling (ODF) process of a liquid crystal display panel.
2. Description of the Related Art
Advanced development for sealant materials and methods thereof, have recently been driven by demand for large-sized liquid crystal displays (LCDs). For large-sized LCD panels (larger than 32 inches), a one drop filling (ODF) process is utilized to fill the liquid crystals of the LCD panels during fabrication thereof. After respectively forming alignment layers on two glass substrates, a sealant is dispersed on one of the two glass substrates. Then, liquid crystals are dropped on the glass substrate having the sealant thereon. Next, the two glass substrates are aligned, and then bonded and assembled. Then, the sealant material is cured. The ODF process takes minimal time and is cost efficient. Therefore, utilizing the ODF process contributes to higher yield rates of display panels made therewith.
The sealant in the ODF process is used to bond the two glass substrates, and also prevent the liquid crystals from pollution, avoid liquid crystal leakage, and avoid water vapor and oxygen from permeating into the LCD panels. Currently, sealant materials used for the ODF process are mainly crystallized acrylic modified epoxy resin. International (PCT) Patent No. WO2004-108790, Europe Patent No. EP1835333, Japan Patent No. JP2007-156183 and JP2008-116825 disclose utilizing an epoxy resin which contains acrylic and epoxy groups on a molecular chain, a mono-functional group-containing acrylic modified epoxy resin, an epoxy resin which contains aliphatic, aromatic or cyclic ester functional group on a molecular chain or an epoxy resin which contains secondary alkyl or tertiary alkyl on a molecular chain for the sealant material. In addition, acrylic monomer used to modify the epoxy resin can have imino groups thereon and the sealant materials may contain a light-shielding colorant. For the acrylic modified bisphenol F epoxy resin, a p,p′-isomer thereof is more than 40%. Meanwhile, the sealant materials further include a UV photosensitive and thermal cured typed curing agent, a thermal cracked free radical typed curing agent or a thermal curing agent of hydrizide, diazide or tertiary amine compounds.